7-2.1 | CLIMATE-INDUCED CHANGES IN THE STRUCTURAL AND FUNCTIONAL DIVERSITY OF EPIFAUNAL COMMUNITIES IN THE SOUTH-EASTERN AND NORTHERN NORTH-SEA

North Atlantic Oscillation (NAO) is the dominant signal of interannual variability in the atmospheric circulation of the North Atlantic region. The NAO Index is an indication of the position and strength of weather systems across the North Atlantic, which in turn determine precipitation, sea surface temperature, direction and flow of marine currents, height of waves, and the stability of the water column in the North Sea. A high index is associated with strong and a low one with weak westerly winds. Consequently, during high NAO winters the moderating influence of the ocean results in unusually warm winter temperatures in the North Sea. In contrast to earlier decades, the NAOI increased to the highest consistently positive values of the century after 1987. Biological long-term studies in the North Sea reveal a significant correlation between the variability of species number, abundance and biomass and the NAOI. In the late 1980s a “regime shift” was related to the significant NAOI increase.

Within this project we study the decadal variability of epifaunal communities in the south-eastern and northern North Sea in relation to environmental and climate factors. Multivariate and geo-statistical analyses will be used to study a) climate-induced changes in community structure and function of epifaunal communities, b) the role of water temperature in mediating these changes and c) the role of neozoa in present and future community structure and function. Model approaches will be used to predict changes in communities due to increasing water temperature.